radiation

noun

ra·​di·​a·​tion ˌrā-dē-ˈā-shən 

1

a

: the action or process of radiating

b

: the process of emitting radiant energy in the form of waves or particles

c(1)

: the combined processes of emission, transmission, and absorption of radiant energy

(2)

: the transfer of heat by radiation compare conduction, convection

2

a

: something that is radiated

b

: energy radiated in the form of waves or particles

3

: radial arrangement

4

: adaptive radiation

radiational

ˌrā-dē-ˈā-shnəl 

-shə-nᵊl

adjective

radiationless

ˌrā-dē-ˈā-shən-ləs 

adjective

radiative

ˈrā-dē-ˌā-tiv 

adjective

Examples of radiation in a Sentence

She was exposed to high levels of radiation.

He goes in for radiation next week.

the sun's radiation of heat

Recent Examples on the Web

Proton therapy is a more precise type of radiation with fewer side effects than conventional radiation therapy. —Michael T. Nietzel, Forbes, 13 Dec. 2024

To be safe, physicians offer the vast majority of people with DCIS the same current standard treatment options: surgery, radiation, and often hormone therapy drugs. —Alice Park, TIME, 12 Dec. 2024

Cancer is typically treated with surgery, radiation and sometimes chemotherapy. —Adrianna Rodriguez, USA TODAY, 12 Dec. 2024

This conclusion was reached thanks to new data about the accelerations of nearby pulsars—rapidly spinning neutron stars that emit beams of radiation that sweep out through space light the beacon of a lighthouse. —Gordon G. Chang, Newsweek, 11 Dec. 2024

Word History

First Known Use

15th century, in the meaning defined at sense 1a

Phrases Containing radiation

• adaptive radiation
• anti-radiation
• background radiation
• Cerenkov radiation
• cosmic background radiation
• electromagnetic radiation
• gamma radiation
• gravitational radiation
• radiation sickness
• radiation therapy
• secondary radiation
• synchrotron radiation
• x-radiation

Kids Definition

radiation

noun

ra·​di·​a·​tion ˌrād-ē-ˈā-shən 

1

: the action or process of radiating

especially : the process of giving off radiant energy in the form of waves or particles

2

: something that is radiated

especially : energy radiated in the form of waves or particles

radiational

-shnəl 

-shən-ᵊl

adjective

Medical Definition

radiation

noun

ra·​di·​a·​tion ˌrād-ē-ˈā-shən 

1

: energy radiated in the form of waves or particles

2

a

: the action or process of radiating

with radiation of the pain there may be tenderness over the sciatic nerve

—J. A. Key

b(1)

: the process of emitting radiant energy in the form of waves or particles

(2)

: the combined processes of emission, transmission, and absorption of radiant energy

3

: a tract of nerve fibers within the brain

especially : one concerned with the distribution of impulses arising from sensory stimuli to the relevant coordinating centers and nuclei

the optic radiations